Another A/C Question: flushing
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
Another A/C Question: flushing
I'm preparing to replace the compressor, accumulator, and orifice tube on my 2000 Corvette. I haven't opened the system yet, nor am I sure of the extent of debris in my system from the failed compressor. Either way, I'm assuming it would be advisable to flush the system.
Does anyone have experience with this? I was planning on using a flush gun (like THIS one) with some flushing solvent. I plan to flush the condenser and will remove and flush the hoses. Is there a "muffler" on one of the hoses that would prevent me from flushing it? Should I flush the evaporator, too? Also, I've read that GM recommends flushing with refrigerant...will flushing via this method be acceptable? Anything else I should know? Upon reassembly I'll also install a compressor suction screen for some insurance.
Thanks in advance.
Rocco
Does anyone have experience with this? I was planning on using a flush gun (like THIS one) with some flushing solvent. I plan to flush the condenser and will remove and flush the hoses. Is there a "muffler" on one of the hoses that would prevent me from flushing it? Should I flush the evaporator, too? Also, I've read that GM recommends flushing with refrigerant...will flushing via this method be acceptable? Anything else I should know? Upon reassembly I'll also install a compressor suction screen for some insurance.
Thanks in advance.
Rocco
Pro
Joined: Jun 2007
Posts: 631
Likes: 3
From: Joppa AL
What I've always done is use a flush gun like in your link and refrig flushing solvent from any FLAPS.
Flush all components then blow shop air through until nothing comes out. I usually let it sit overnight just to be sure.
Leave your vac pump on it for several hours to be sure and then recharge.
Some flush with refrig, some with nitrogen. Any of these will work. What you're trying to do is get rid of any nasty metal pieces that got pumped into the system when the comp failed.
I assume your comp self destructed. Best way to tell if the system is contaminated is look closely at the orfice tube. The trash will collect there. If that's clean, you're probably OK.
Flush all components then blow shop air through until nothing comes out. I usually let it sit overnight just to be sure.
Leave your vac pump on it for several hours to be sure and then recharge.
Some flush with refrig, some with nitrogen. Any of these will work. What you're trying to do is get rid of any nasty metal pieces that got pumped into the system when the comp failed.
I assume your comp self destructed. Best way to tell if the system is contaminated is look closely at the orfice tube. The trash will collect there. If that's clean, you're probably OK.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
PLASTICFAN has some good info! 
If you use shop air, it most likely contains moisture and maybe even compressor oil unless its filtered and dried. Nitrogen or R-134 is dry and wont leave any residue. Any way you do it, if it has debris in the system, it will come out. Ive had some systems that were so contaminated that it took two flushes to get them clean.
I used plain old shop air but made sure my compresser tank was drained and used a paint gun line filter to help get the air and as clean as possible. As PLASTICFAN stated, I also allowed the vacuum pump to run longer than I usually do. Another trick to help get a good vacuum on the system is to use a heat gun and warm up the condenser coil which will help get the vacuum to draw down that much further once you remove the heat and allow it to cool back down. Drawing a vacuum removes the moisture in the system and non condensible gases. Once you evacuate the system, hook up your manifold to the can of R-134, purge the air out of the manifold hose, hook it up to the system and purge in the R-134 to replace the vacuum.
Charge it up to the shop manual specs. Theres an EXCELLENT post on recharging out there!
Bill
If you use shop air, it most likely contains moisture and maybe even compressor oil unless its filtered and dried. Nitrogen or R-134 is dry and wont leave any residue. Any way you do it, if it has debris in the system, it will come out. Ive had some systems that were so contaminated that it took two flushes to get them clean.
I used plain old shop air but made sure my compresser tank was drained and used a paint gun line filter to help get the air and as clean as possible. As PLASTICFAN stated, I also allowed the vacuum pump to run longer than I usually do. Another trick to help get a good vacuum on the system is to use a heat gun and warm up the condenser coil which will help get the vacuum to draw down that much further once you remove the heat and allow it to cool back down. Drawing a vacuum removes the moisture in the system and non condensible gases. Once you evacuate the system, hook up your manifold to the can of R-134, purge the air out of the manifold hose, hook it up to the system and purge in the R-134 to replace the vacuum.
Charge it up to the shop manual specs. Theres an EXCELLENT post on recharging out there!
Bill
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
Thanks to the both of you for the info!
When flushing, does it matter whether I flush from the inlet or outlet side of each component?
I was a bit unsure of whether to flush the evaporator since I had read that due to the design of some evaporators they had a tendency to retain the flushing solvent and that it is difficult to get them cleaned out. So it's okay to flush both hoses, too?
Thanks a million!
When flushing, does it matter whether I flush from the inlet or outlet side of each component?
I was a bit unsure of whether to flush the evaporator since I had read that due to the design of some evaporators they had a tendency to retain the flushing solvent and that it is difficult to get them cleaned out. So it's okay to flush both hoses, too?
Thanks a million!
Pro
Joined: Jun 2007
Posts: 631
Likes: 3
From: Joppa AL
Thanks to the both of you for the info!
When flushing, does it matter whether I flush from the inlet or outlet side of each component? NO
I was a bit unsure of whether to flush the evaporator since I had read that due to the design of some evaporators they had a tendency to retain the flushing solvent and that it is difficult to get them cleaned out.
That is also true of condensers. Blowing it dry, giving it time to evaporate and pulling a good vac is the key. Bill's point on air is well taken too. Keep it as clean and dry as you can.
So it's okay to flush both hoses, too? YES
Thanks a million!
When flushing, does it matter whether I flush from the inlet or outlet side of each component? NO
I was a bit unsure of whether to flush the evaporator since I had read that due to the design of some evaporators they had a tendency to retain the flushing solvent and that it is difficult to get them cleaned out.
That is also true of condensers. Blowing it dry, giving it time to evaporate and pulling a good vac is the key. Bill's point on air is well taken too. Keep it as clean and dry as you can.
So it's okay to flush both hoses, too? YES
Thanks a million!
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
Great, now I feel confident I know what to do.
One last question, though: After I flush everything and replace the compressor, accumulator, and orifice valve, I'll add PAG oil to the compressor, accumulator, evaporator, and condensor (I found the required amounts in another thread). Then after I reassemble everything I'll pull a vacuum for 45 min or so. Will pulling a vacuum remove any of this oil? Will I have to add more oil when recharging with r134?
Thanks again. A beer (or three) is in order for both of you.
One last question, though: After I flush everything and replace the compressor, accumulator, and orifice valve, I'll add PAG oil to the compressor, accumulator, evaporator, and condensor (I found the required amounts in another thread). Then after I reassemble everything I'll pull a vacuum for 45 min or so. Will pulling a vacuum remove any of this oil? Will I have to add more oil when recharging with r134?
Thanks again. A beer (or three) is in order for both of you.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
No! Your oil will be fine if you add all the oil that is called out in the procedure for EACH componet in the system. You can a little bit more (the accumulator will hold it ) to make sure you have the correct ammount.
I would leave the vacuum on about two-three hours at a minumum.
Then secure the vacuum an MAKE SURE it holds the system holds vacuum once the pump is secured. Make sure that you remove the pump.
Bill
I would leave the vacuum on about two-three hours at a minumum.
Then secure the vacuum an MAKE SURE it holds the system holds vacuum once the pump is secured. Make sure that you remove the pump.
Bill
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Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
Update: I just finished R&R of my compressor and flushing the system. Looked like the compressor was spewing out all kinds of crap...the oil in it looked like graphite paste! Have a look at the orifice tube below! I flushed each component twice (used a half gallon of flushing solvent) to get everything clean and pumped compressed air through each component for 10 min or so to thoroughly dry them. I then replaced all o-rings (lubing them with dielectric grease), added 2.5oz of PAG 46 to the compressor, 1 oz to the condensor, 1/2 oz to the low pressure line, and 1/2 oz to the high pressure line. I'll add 2.5 oz to the acumulator and 2 more oz when I charge the system for a total of 9 oz.
I would be done right now, but the accumulator I ordered doesn't fit. I'll have to wrap up tomorrow. For now the system is all together except for the accumulator.
Could the new oil be contaminated by moisture while I leave the system open until I get the correct accumulator? I plan on leaving it on a vacuum for 4-5 hours tomorrow...
I've got a bunch more pics of the process and will post when I'm finished up.
I would be done right now, but the accumulator I ordered doesn't fit. I'll have to wrap up tomorrow. For now the system is all together except for the accumulator.
Could the new oil be contaminated by moisture while I leave the system open until I get the correct accumulator? I plan on leaving it on a vacuum for 4-5 hours tomorrow...
I've got a bunch more pics of the process and will post when I'm finished up.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You should be fine. Just put something over the opening/s and when you apply the vacuum it will take care of any moisture. The accumulator has a desicant bag inside it and will handle ANY moisture that the vacuum doesnt take care of.
Dont forget to add the correct ammount of oil to your accum/dryer.
BC
Dont forget to add the correct ammount of oil to your accum/dryer.
BC
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
Next time lube the orings with the pag oil, not dielectric grease.
Also turn the compressor by hand, the center part, so when it comes on you wont be compressing oil.
If you want to heat up the parts, start the engine and let idle for a while with the hood closed. When it and the underhood temps and all AC parts are nice and toasty, then you can evacuate with the vac pump and the moisture will evaporate faster.
Also turn the compressor by hand, the center part, so when it comes on you wont be compressing oil.
If you want to heat up the parts, start the engine and let idle for a while with the hood closed. When it and the underhood temps and all AC parts are nice and toasty, then you can evacuate with the vac pump and the moisture will evaporate faster.
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
Okay, just installed the correct accumulator after adding 2.5 oz of PAG oil to it. I ran the vacuum pump for 20 min, closed both the high/low valves, and waited another 20 min or so. The system held at ~29", so it looks like I'm good to go!
I have the vacuum pump running now and will let it go for 5-6 hours, then I'll charge it and be done! I'm getting excited for cold a/c, especially since it supposed to hit triple digit temps this week.
I was planning to recharge with regular r134a, but I've had a few people tell me that I would be better off going with the stuff that has the synthetic "Sub-Zero" booster because it cools better...thoughts?
Plasticfan, I notice your pics are gone from your "AC 101" thread. Do you still have the a/c pressure chart? I'd like to refer to it while I'm charging the system.
I'm getting close!
I have the vacuum pump running now and will let it go for 5-6 hours, then I'll charge it and be done! I'm getting excited for cold a/c, especially since it supposed to hit triple digit temps this week.
I was planning to recharge with regular r134a, but I've had a few people tell me that I would be better off going with the stuff that has the synthetic "Sub-Zero" booster because it cools better...thoughts?
Plasticfan, I notice your pics are gone from your "AC 101" thread. Do you still have the a/c pressure chart? I'd like to refer to it while I'm charging the system.
I'm getting close!
Last edited by RoccoC5; Apr 27, 2008 at 04:37 PM.
Pro
Joined: Jun 2007
Posts: 631
Likes: 3
From: Joppa AL
I've heard lots of pro and con about diff refrig over the years but I've never really tried them.
It might work but our C5's have a great AC system and the 134 will freeze you out of the cabin.
I fixed the missing images, don't know what was wrong, must have been an ImageCave glitch. The chart is there now.
You're really knocking this thing out. Are you going to open your own shop?
It might work but our C5's have a great AC system and the 134 will freeze you out of the cabin.
I fixed the missing images, don't know what was wrong, must have been an ImageCave glitch. The chart is there now.
You're really knocking this thing out.
Are you going to open your own shop?
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 966
Likes: 9
From: Phoenix AZ
All done, though! And the a/c's colder than it's ever been!
I put together a simple write-up on the process. Download it HERE. I'll implement any feedback you guys have and then post it up in C5 tech.
Thanks again for everyone's help!
Last edited by RoccoC5; Apr 28, 2008 at 08:44 PM.
